I think Huckabee wins these states in the end, though possibly has to spend more time shoring up the base there. Remember, evangelicals are only a portion of the Republican base, even in the South. Plenty of country-club conservatives who care more about keeping taxes low and the government small will need a lot of convincing to vote for Huckabee.
I think Huckabee would, however, lose badly in the Northeast (where Bush at least had a chance in New Hampshire and Maine) and in the marginal Western states that Clinton carried. And a third-party libertarian run could muck with Montana or Wyoming.
So, this is what the map would look like
Huckabee v. Any Big Three Democrat
Yeah, and maybe Missouri could go Democratic as well.